But any euphoria was quickly overshadowed by an ominous warning from Hamas that it rejected the truce and was not bound by it. That means Hamas can literally blow up the peace process with just one suicide bombing. So getting the cease-fire to hold will be a major test for Mahmoud Abbas. If groups like Hamas break the truce, Israel will demand a crackdown, but Abbas fears that could lead to civil war. If Abbas allows Hamas to call the shots, then Israel will cast him off as another Palestinian leader who cannot deliver.